A variety of methods are known for calibrating network analyzers, for example from German laid-open patent applications DE 44 33 375 A1, DE 39 12 795 A1 and DE 102 42 932 A1. German laid-open patent applications DE 102 35 221 A1 and DE 199 18 960 A1 describe a method for calibrating a network analyzer with more than two measuring ports.
In practice, the calibration method according to the 10-term model for network analyzers with three measuring receivers and the method based on the 7-term model which, however, uses a network analyzer with four measuring receivers, have become established. In these methods, two measuring ports of the network analyzer are connected to three different standards of which various parameters are known. In the previously used 7-term method, however, the requirement was made that both the first and second standards were ideally matched, i.e. that their reflection factors were equal to zero. This limitation is substantial and implies a significant reduction in the standards that are available.